Electrovibrant high-voltage supply



Dec. 1l, 1951 A, C, CHRISTY 2,578,043

ELECTROVIBRANT HIGH-VOLTAGE SUPPLY Filed Dec. 28, `1948 H\GH VOLTAGE v HIGH 1 Z/ VOLTAGE Patented Dec. 11, 1951 UNITED STATES PATENT GFFICE 2,578,043 ELncTRovIBRANT nien-VOLTAGE sUrritrv Alexander C. Christy, Morgantown, W. Va.

Application December 28, y1948, Serial No. 67,742

(Cl. Z50-36) Claims. 1

This invention relates to high voltage generation, and more particularly to electronic high voltage generators for use as sources of high voltage in television projection systems, electronic ignition systems for internal combustion engines, radar transmission, photo-ilash units, and nu- Inerous other devices employing high voltages.

vA main object of the invention is to provide method and means for developing high voltages employing very simple and inexpensive components, involving no moving parts, and operating at high einciency.

A'iurther object of the invention is to provide an improved high voltage generator which is easy to construct. employs only a iew components, is compact in size, and requires no amplifying equipment.

A still further object of the invention is to prew vide an improved electronic high voltage generator which is rugged in construction, empioys standard parts, and which is especially 'suitable for use as a high voltage source for cathode ray tubes as employed in television and radar, as a high Voltage source for ignition in internal coinbustion engines, and for numerous additional devices requiring high voltage.

Further objects and 'advantages of the invention will become apparent from the following den scription and claims, and from the accompanying drawings, wherein:

Figure 1 is a schematic diagram of an electronic high voltage generator constructed in accordance with the present invention;

Figure 2 is a schematic diagram illustrating another form of electronic high voltage generator according to the present invention;

` Figure 3 is a graph showing the form of the voutput voltage wave generated by the devices of lFigures 1 and`2.

Figure l is a schematic diagram illustrating another form of the invention wherein a cold cathode tube is employed.

Referring to the drawings, and more particularly to Figure 1, II designates a grid-controlled gaseous conduction tube, such as a thyratron or 'similar type of gas-filled triode. Tube I I is shown as having a cathode I2, an anode I3, and a control grid I4. The tube is filled with suitable inert gas, such as neon, argon, hydrogen, mercury trance of alternating high-voltage current into the direct current supply source and also limits the D. C. current iiow through the gaseous conduction tube li. The negative terminal of the direct current supply source is connected to cathode I2 through a biasing resistor It. rlhe grid ill of the tube is connected to the negative terminal ci the direct current supply source through a leak resistor I'I.

Connected in series across the anode i3 and the cathode l2 are a capacitor i3 and the primary IS oi the high-voltage output transformer 20. rEhe secondary of transformer 2G is shown at El and preferably has many more turns than the priniary IQ.

The cathode resistor I may be ci a variable type, as shown, so that the bias voltage ci the grid i4 may be adjusted to make the gaseous tube I I conduct at different discharge potentials oi the condenser through the coil I9, thereby controlling the amplitude of the output voltage in the sec ondary 2I.

When the source of direct current is connected to the circuit of Figure l, a large current initially flows through the cathode resistor l and primary I9 to charge the condenser i8. rlhis produces a voltage drop across resistor IS which biases grid id suflicientlv negative to prevent the gaseous tube from conducting. The charging circuit has relatively low resistance, allowing charging to occur rapidly. As the charge on the condenser I8 increases, the charging rate decreases, reducing the current flow through cathode resistor rl'his eventually decreases the negative bias on grid I to a value where ionization of the gas in tube I`I occurs, allowing the tube to conduct. The condenser I3 then rapidly discharges through primary I9 and tube I I. When the charge on the condenser is substantially dissipated, the tube ceases to conduct and remains in a non-conducting state as the condenser i8 again is charged. While the charging rate is high, grid I4 is biased sufficiently negative to prevent tube from conducting, as above stated. As in the previous cycle, discharge or the condenser occurs when the charging rate drops to a value insuiiicient to pro-- duce cut-off bias across resistor' l.

The operation of tube i I in the circuit of Figure 1 may be explained as follows:

Assuming resistor I6 to have a value such that in the absence of the output circuit containing condenser I8 and primary Iz'l, tube i! would be biased not quite to cut-oil, the charging current passes through said resistor to thereby in crease the voltage drop across the resister to a value greater than the cut-off bias value. This causes tube II to cut ofi until condenser I8 has become charged to that point where the charging current through resistor I6 fails to produce cutoff bias voltage across the resistor. Tube I I then conducts heavily and condenser I8 dissipates rapidly, since there is very little resistance in its discharge circuit. A heavy-current pulse flows through primary I9 in a very short time period. This induces a very high voltage in said primary, since the induced voltage e in an inductance L as a function of, current i through the inductance and time t is given by:

At the initiation of the discharge of the condenser I8, the current through primary I9'increases rapidly. A peak current is reached in said primary. Prior to the reaching of this peak current, the induced voltage across primary I9 has a polarity such that cathode I2 is negative with respect to the negative terminal of the voltage source. Grid I4, therefore, in effect has a positive bias and does not interfere with current iiow through the tube. After the peak current has been reached in primary I9, the current begins to decrease with time, which reverses the polarity of the induced voltage across said primary. Cathode I2 becomes positive with respect to the negative terminal of the voltage source, creating a negative bias on grid I4. Since the induced voltage is high, said negative bias drives tube I I deep into cut-oli. By the time tube II cuts cii, condenser I8 is suiciently dissipated to receive a new charge. Charging current then vflows through resistor I6, maintaining the cut-off bias on the tube, as above described, until the charging rate decreases below the value necessary to develop cut-oli bias, repeating the above-described cycle. Referring to Figure 3, the charging current through primary IS induces in secondary winding 2l a voltage wave portion shown at 22. Discharge of condenser I8 produces in secondary 2| a steeply-rising voltage wave portion shown at 23. As the peak of the current pulse through primary I9 occurs, a voltage peak 2li appears across secondary 2l. The reversal of polarity of the induced Voltage in primary I9 coincides with the steeply-descending voltage wave portion 25 of Figure 3, during which tube II is driven into cut-off. As the new charging cycle of condenser I8 begins, the next trough 22 appears in the voltage Wave across secondary 2i.

In the form of the invention shown diagrammatically in Figure 2, the primary I9 of the output'transformer 2i] is connected between condenser I8 and the negative terminal of the D. C. voltage source instead of between condenser I8 and cathode I2, as in Figure 1. A condenser 25 is connected across resistor I5. When the D. C. source voltage is applied to the circuit of Figure 2, a charging current initially flows through condenser I8 and primary I9, in effect shunting tube I I and holding the voltage between plate I3 and cathode i2 below the potential required to ionize the tube until condenser I8 has become substantially charged. As condenser i8 becomes charged, the voltage between plate I3 and cathode I2 rises until it eventually reaches the required ionizing potential. Tube II then conducts. Condenser I8 discharges and a heavycurrent pulse flows through tube II and primary i8. Prior to the attainment of peak current in primary I9, the polarity of the induced voltage in said primary opposes the voltage drop developed by the discharge current across resistor I6, preventing grid I4 from becoming sufilciently negative to cut ofi the tube. After peak current in primary I9, the induced voltage therein reverses in polarity and allows grid I4 to reach cut-olf negative bias. Tube I I no longer conducts. By this time, condenser I8 is substantially discharged. The cycle then repeats. Condenser 26 acts as a by-pass for part of the pulsating current in the discharge circuit and regulates the degree of the excursions of voltage on the grid I4. The shape of the voltage Wave obtained across the terminals of the secondary 2l is substantially the same as obtained in the circuit of Figure 1 and shown in Figure 3.

Repetition rates of the output voltage pulses may be made as high as 20,000 per second, since the polarity of capacitor I8 in either of the above-described forms of the invention, reverses during discharge, lowering the required deionization period of the tube Ii. Output voltages as high as 60,000 volts may be obtained.

The gaseous conduction tube has an operating efiiciency of the order of 98% because of the low voltage drop of the tube and because there is no power dissipated in the anode when the gaseous tube is not conducting. The tube is, therefore, capable of delivering great amounts of power. In an actual working model an output of 20,000 volts at 2 milliamperes was obtained with an input of 350 volts current at milliamperes in a unit measuring 2 inches by 31/2 inches in size.

The high voltage output may be employed directly to provide ignition voltages for internal combustion engines, or in conjunction with a conventional high voltage rectier as a source of high voltage for television projection systems.

Figure 4 shows diagrammatically a form of the invention employing a cold cathode gaseous conduction tube I I The positive voltage is applied to the plate I3 through a limiting resistor I5', charging the condenser I8' which is in series with the primary coil I9. The series-connected condenser I8 and coil I9' are connected across tive with respect to cathode I2 to initiate the conduction of tube II. When the condenser is charged to the ionization potential of the tube Ii' and discharges, a heavy current flows instantaneously through the tube II and primary I9', inducing a high voltage in the secondary 2|. After discharge, the tube I I' is in a non-conducting state, allowing condenser I8 to receive another charge, whereby the cycle is repeated. By using a cold cathode tube, as in Figure 4, the need for a source of filament current for the tube is eliminated.

Although shown in the drawings as employing tubes of the triode type, multiple grid tubes, such i .as tetrodes, pentodes, and the like, may also be employed within the spirit of the present linvention.

While certain specific embodiments of electronic high voltage generating devices have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention, except as defined by the scope of the appended claims.

What is claimed is:

l. A high voltage generator of the character described comprising a gaseous conduction triode, a source of direct current potential. nonreactive means connecting the plate of said triode to the positive terminal of said source, means connecting the grid of said triode to the negative terminal of said source, a grid-biasing resistor connected between the cathode of said triode and said negative terminal, and a `reactive circuit connecting the plate to said cathode, said circuit including a condenser and the primary of a step-up transformer connected in series, whereby initially the charging current charging the condenser fiows through said resistor and provides a bias preventing the triode from conducting, said bias being removed when the condenser becomes charged, allowing the triode to conduct, and causing the condenser to discharge through said primary, the discharge current producing a high induced voltage in the secondary oi' said step-up transformer.

2. A high voltage generator of the character described comprising a gas triode, a source of direct current, the plate of said triode being connected to the positive terminal of said source, a grid biasing resistor connected between the cathode of said triode and the negative terminal of said source, means connecting the grid of the triode to said negative terminal, a condenser, a step-up transformer, and means connecting the condenser and the primary of said transformer in series between said plate and said cathode, whereby initially the charging current charging the condenser flows through said resistor and provides a bias preventing the triode from conducting, said bias being removed when the condenser becomes charged, allowing the triode to conduct, and causing the condenser to discharge through said primary, the discharge current producing a high induced voltage in the secondary of said transformer.

3. A high voltage generator of the character described comprising a gas triode, a source of direct current, the plate of said triode being connected to the positive terminal of said source, a grid biasing resistor connected between the cathode of said triode and the negative terminal of said source, means connecting the grid of the triode to said negative terminal, a condenser, a step-up transformer, said condenser and the primary of the transformer being connected in series between said plate and said cathode, whereby initially the charging current charging the condenser flows through said resistor and provides a bias preventing the triode from conducting, said bias being removed when the condenser becomes charged, allowing the triode to conduct, and causing the condenser to discharge through said primary, the discharge current producing a high induced voltage in the secondary of said step-up transformer.

4. A high voltage generator of the character described comprising a gas triode, a source of direct current, the plate of said triode being connected to the positive terminal of said source, a grid biasing resistor connected between the cathode of said triode and the negative terminal of said source, means connecting the grid of the triode to said negative terminal, a condenser, a step-up transformer, said condenser and the primary of the transformer being connected in series between said plate and said negative terminal, whereby initially the charging current charging the condenser flows through said condenser and primary, providing relatively low plate potential preventing the triode from con ducting, said plate potention being increased when the condenser becomes charged, allowing the triode to conduct, and causing the condenser to discharge through said primary, the discharge current producing a high induced voltage in the secondary of said transformer.

5, A high voltage generator of the character described comprising a gas triode, a source of direct current, the plate of said triode being con nected to the positive terminal of the source, means connecting the cathode of said triode to the negative terminal of said source, circuit means connecting the grid and cathode of the triode and including a resistor arranged to provide a bias on the grid of the triode, a condenser, a step-up transformer, and circuit means connecting said condenser and the primary of said transformer in series between the plate and the cathode of the triode, said circuit means being arranged to maintain the triode non-conducting while the condenser is charging and to allow the triode to conduct when the condenser is substantially charged, whereby the condenser discharges through said primary and the triode, the discharge current causing a high voltage to be induced in the secondary of said transformer.

ALEXANDER C. CHRISTY.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,898,827 Franklin et al Jan. 28, 1931 1,926,181 Schramm Sept. 12, 1933 2,097,066 Hoover Oct. 26, 1937l 2,108,219 Swart Feb. 15, 1938 2,251,877 Hagerdorn Aug. 5, 1941 FOREIGN PATENTS Number Country Date 426,002 Great Britain Mar. 26, 1935 206,222 Great Britain July 31, 1939 

